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Implement MEMCPY natively in terms of rep movs*

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llvm-svn: 19468
This commit is contained in:
Chris Lattner 2005-01-11 06:19:26 +00:00
parent b2b08a8bc1
commit bb63a09cd1
1 changed files with 45 additions and 1 deletions
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46
lib/Target/X86/X86ISelPattern.cpp
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@ -50,7 +50,6 @@ namespace {
computeRegisterProperties();
setOperationUnsupported(ISD::MEMCPY, MVT::Other);
setOperationUnsupported(ISD::MEMMOVE, MVT::Other);
setOperationUnsupported(ISD::MUL, MVT::i8);
@ -2088,6 +2087,51 @@ void ISel::Select(SDOperand N) {
BuildMI(BB, Opcode, 0);
return;
}
case ISD::MEMCPY:
Select(N.getOperand(0)); // Select the chain.
unsigned Align =
(unsigned)cast<ConstantSDNode>(Node->getOperand(4))->getValue();
if (Align == 0) Align = 1;
// Turn the byte code into # iterations
unsigned CountReg;
unsigned Opcode;
switch (Align & 3) {
case 2: // WORD aligned
CountReg = MakeReg(MVT::i32);
if (ConstantSDNode *I = dyn_cast<ConstantSDNode>(Node->getOperand(3))) {
BuildMI(BB, X86::MOV32ri, 1, CountReg).addImm(I->getValue()/2);
} else {
unsigned ByteReg = SelectExpr(Node->getOperand(3));
BuildMI(BB, X86::SHR32ri, 2, CountReg).addReg(ByteReg).addImm(1);
}
Opcode = X86::REP_MOVSW;
break;
case 0: // DWORD aligned
CountReg = MakeReg(MVT::i32);
if (ConstantSDNode *I = dyn_cast<ConstantSDNode>(Node->getOperand(3))) {
BuildMI(BB, X86::MOV32ri, 1, CountReg).addImm(I->getValue()/4);
} else {
unsigned ByteReg = SelectExpr(Node->getOperand(3));
BuildMI(BB, X86::SHR32ri, 2, CountReg).addReg(ByteReg).addImm(2);
}
Opcode = X86::REP_MOVSD;
break;
default: // BYTE aligned
CountReg = SelectExpr(Node->getOperand(3));
Opcode = X86::REP_MOVSB;
break;
}
// No matter what the alignment is, we put the source in ESI, the
// destination in EDI, and the count in ECX.
unsigned TmpReg1 = SelectExpr(Node->getOperand(1));
unsigned TmpReg2 = SelectExpr(Node->getOperand(2));
BuildMI(BB, X86::MOV32rr, 1, X86::ECX).addReg(CountReg);
BuildMI(BB, X86::MOV32rr, 1, X86::EDI).addReg(TmpReg1);
BuildMI(BB, X86::MOV32rr, 1, X86::ESI).addReg(TmpReg2);
BuildMI(BB, Opcode, 0);
return;
}
assert(0 && "Should not be reached!");
}